Conventionally, echo signal processing devices for calculating information regarding an echo signal received by an antenna based on the echo signal, have been known. For example, JP1991-262990A discloses a wave observation radar for calculating echo signal information (e.g., a wave direction and a wave velocity) by determining a processing range (analytic area) of sea surface reflection signals in a predetermined area and performing two-dimensional FFT (Fast Fourier Transform) for the analytic area.
Meanwhile, conventionally, such analytic area described above is set with reference to a position of, for example, a ship in which the radar is installed. Specifically, in any radar image which is updated with time, the position of the analytic area is fixed to the position with reference to the ship. However, in this case, the position of the analytic area also moves as the ship moves, and therefore, an image of a wave extracted from the analytic area contains a relative velocity component (Doppler component) to an actual wave. As a result, accurate echo signal information cannot be calculated.